Method of and apparatus for cooling concrete aggregates



Dec. 20, 1955 A. J. VINCENT 2,727,734

METHOD OF AND APPARATUS FOR COOLING CONCRETE AGGREGATES Filed June 14,195] 3 Sheets-Sheet l 32 STOCKPILE WATER SUPPLY SURGE TANK REFRIGERATIONPLANT WASTE POND MIXER INVENTOR. (lrchie J. Vincenl BY M -don @J \MALOTAhaw ATT'YS Dec. 20, 1955 J; v 2,727,734

METHOD OF AND APPARATUS FOR COOLING CONCRETE AGGREGATES Filed June 14,1951 5 Sheets-Sheet 2 FIG?) In INVENTOR.

QrBhIQ J. Vincent BY AT T'YS United States Patent 0 bed METHOD OF ANDAPPARATUS FOR COOLING CONCRETE AGGREGATES Archie J. Vincent, Champaign,Ill., assignor to The C. S. glohnson Company, Champaign, 11L, acorporation of linois Application June 14, 1951, Serial No. 231,561

8 Claims. (Cl. 259-155) The present invention relates to a method of andapparatus for cooling concrete aggregates. More specifically, theinvention relates to a method of and apparatus for the selectiveprecooling of the relatively coarse constituents of a concrete batch toa temperature which is at least as low as the degree of temperaturenecessary to attain a desired placement temperature of the final mix.

Modern specifications for large installations, particularly whereconcrete dams are concerned, require that the concrete shall not beplaced if the temperature of the final mix exceeds a predeterminedspecified temperature. accommodate these specifications, recent practiceinvolves various methods of which the most prevalent are: (l) the use ofcold air blasts for cooling the aggregate; (2) the cooling of the mixwater, and (3) the use of ice for batching purposes. these threeexpedients, either singly or in combination, in an effort to attain thedesired placement temperature. In many instances it has been found thateven when all three expedients have been resorted to, the desired lowplacement temperature cannot be attained.

in addition to the frequentinefiectiveness of such methods of cooling,the fact that extremely complicated, expensive and cumbersome equipment,as well as additional manpower, must be employed has lead to ratherdiscouraging results. Since each large installation presents specialproblems and new methods of approach, a detailed discussion of all themany cooling expedients that have heretofore been resorted to is notwithin the scope of this specification, and it is deemed sufiicient tostate that in certain instances not only have the coarse aggregates beencooled but additionally heat exchangers have been provided whereby thefine aggregate or dry sand has been cooled with the sand flowing throughwater-jacketed fines. The use of silos for chilling the coarseaggregates has also been resorted to wherein the silos are partiallyfilled with chilled water, the ggregates then introduced, andcirculation of water by means of a pumping system maintained for apredetermined period of time, followed by drainage of the silos anddischarge of the contents thereof. Such an inundation process hasinvolved transportation di-fiiculties and associated cooling problems.In order to maintain the low temperature attained in the precoolingprocess outlined above while transporting the aggregates and storingthem in the overhead bins at the mixing plant, provisions have had to bemade to maintain the storage and transfer areas at a low temperature. Inone instance, this has required the erection of an insulated building toenclose the overhead bins as well as an insulated enclosure for theaggregate conveyor line leading from the cooling plant to .the mixingplant. An air conditioning unit has been employed in the cooling plantbuilding to circulate cooling air throughout the areas where the cooledaggregates .are stored or handled.

The present invention is designed to overcome the above notedlimitations, principally of manpower and equipment, that are attendantupon the use of present day practice in the 'precooling of aggregatesprior to mixing Various installations have employed ice and subsequentplacement thereof, and toward this end it contemplates, briefly, theprovision of a spray bin in advance of the mixer installation toconsolidate practically all of the necessary handling of the aggregatesprior to the mixing thereof in one location and to thereby eliminatemuch of the heretofore necessary equipment and manpower. According tothe present invention it is contemplated that one workman shall berequired to direct the material into the areas provided for it and todispatch the material from the stock pile of aggregates, while a secondworkman is required to control the direction of water flow and tooperate the discharge gates employed in connection with the process.

In addition to the multiple bin construction briefly outlined above, theequipment employed involves a .conveyor for conducting coarse aggregatesto the spray bin assembly from the stock pile, a bypass conveyor forconducting fine aggregate such as sand from the stock pile, and a mixerplant feed conveyor for receiving the cooled aggregate and sand from thespray bin assembly and the bypass conveyor, respectively, and forconducting them jointly to the mixer plant wherein they may be furthertreated by conventional processes prior to and during the mixingoperation preparatory to placement of the batch. The equipment also mayinclude a settling pond or surge tank, to which fresh coolant water maybe supplied and to which expended coolant water resulting from thespraying operation may be returned, a refrigeration plant or heatexchanger for cooling the water. supplied from the surge tank to thespray bin construction, a shaker screen apparatus for equalizing thedistribution of residual moisture in the aggregate after sprayingthereof, a waste pond or the like for receiving the waste products suchas silt from the shaker screen, together with such equipment as thenecessary coolant conduits, valves for controlling or directing the flowof .the coolant, and gates and other directional control mechanism forthe aggregate material.

The provision of a method of and apparatus for cooling aggregates of thecharacter briefly outlined above being the principal object of theinvention, another object is to provide such a method and apparatus bymeans of which selective control of the treatment of the material may beobtained in order that aggregates of uniform water content may beforwarded to the mixing plant from the precooling station.

A further object of the invention is to provide a novel apparatus forprecooling the relatively coarse aggregates preparatory to the mixing ofthe concrete batch, together with means for insulating the precooledmaterial during the transfer .to the mixing plant in order that thereshall be no transfer .of heat from the ambient atmosphere to theprecooled materials prior to their arrival at the mix in plant.

Yet another object is to provide .a method and apparatus for precoolingaggregates which, in addition to very materially reducing the manpowerand equipment necessary to obtain the desired results, affords a systemof operation which is highly selective in its treatment of the materialsand which may be conducted with a minimum of effort on the part of theoperators thereof.

Other objects and advantages, not at this time set forth, will becomemore readily apparent as the nature of the invention is betterunderstood.

In the accompanying two sheets of drawings forming .a part of thisspecification, a preferred embodiment of the invention has been shown.

In these drawings:

Figure lis a flow chart illustrating the method employed in connectionwith .the invention and showing schematically a novel type of spray binassembly employed in practicing the same.

Fig. 2 is a side elevational view, almost entirely schematic in itsrepresentation, of the spray bin assembly as utilized in a typicalinstallation.

Fig. 3 is a schematic plan "iew of the installation of Fig. 2.

Fig. 4 is a circuit diagram of an electric distribution control systemwhich may be employed in connection with the invention.

Fig. 5 is an hydraulic circuit diagram of a gate control system whichmay be employed in connection with the invention, and

Fig. 6 is a time chart showing a purely arbitrary schedule of operationsof the apparatus for a selected concrete installation.

While the invention is susceptible of various modifications andalternative constructions, there is shown in the drawings and willherein be described in detail the preferred embodiment, but it is to beunderstood that it is not thereby intended to limit the invention to theform disclosed, but it is intended to cover all modifications andalternative constructions falling within the spirit and scope of theinvention as expressed in the appended claims.

Referring now to the drawings in detail and in particular to Fig. 2, thecentral mixing plant installation, designated in its entirety at 10, maybe of any suitable design and will be availed of the usual featuresassociated with such plants including the material batchers 12, cementtank 14, aggregate compartments 16, charging hopper and distributor 17,collector cone 18 and all the other accoutrements common to suchinstallations. In the present in stance the installation may include arefrigeration and ice plant 20, ice elevator 22, ice screw 24 and icebatcher and chute 26, all for delivery of batched ice to the batchmaterials in order to maintain the low delivery temperature of theprecooled aggregate materials conducted to the mixing plant according tothe present invention and to further lower this temperature, ifnecessary, to attain the required low placing temperature of the mixedconcrete materials.

The character of the central mixing plant 10 may vary widely fordifferent installations and no claim is made herein to any noveltyassociated therewith. It is simply the aim of the present invention todeliver the materials undergoing batching, particularly the coarseaggregates delivered to the aggregate compartments 16, at the lowesttemperature practicable for further treatment at the mixing plant. Onetype of installation with which the present invention may be associatedhas been disclosed by illustration and description in a publicationentitled Johnson Concrete Plants, Portable and Stationary, which is acatalogue of the C. S. Johnson Company of Champaign, Illinois. Thisinstallation is illustrated on page 13 of the publication and is widelyknown as the Johnson Octo-Bin.

The installation illustrated at 10 is of the Octo-Bin type and isillustrated in Figs. 1, 2 and 3 as having six aggregate compartmentsalthough the enclosure for the compartments is provided with eightsides. Obviously, a greater or lesser number of aggregate compartmentsmay be provided if desired.

The materials of a batch to be charged into any one of the batchers 12are carried to and fed into the distributing hopper 17 by means of aconveyor 28 leading from a spray bin installation or assembly 30 bymeans of which the coarse aggregates are cooled according to the presentinvention.

Located more or less remotely in relation to the central mixing plant10, and also to the spray bin installation 36 are the supply sources ofthe different aggregate materials such as stone of different sizes,gravel of dilferent sizes, sand, etc. These sources may be stock pilesor bins, such being immaterial to the present invention and the sourcesare designated at 32. The supply sources for the aggregates are disposedabove a conveyor 34 and a series of measuring batchers 35 may beprovided, one for each supply source. Suitable means may be provided foroperating the batchers 35 in accordance with the demand for thedilferent aggregate materials required at the spray bin assembly and atthe mixing plant. The conveyor 34 terminates at its discharge end in apivoted distributor 36 which may be either manually operated or operatedelectrically, pneumatically, hydraulically or otherwise by remotecontrol. According to a preferred embodiment of the invention, remotecontrol of the distributor 36 is desirable in order that the same may beoperated under the control of a workman at the spray bin assembly 30,all in a manner that will become clear presently. An electrical controlmechanism for the pivoted distributor 36 has been shown in Fig. 4 andwill be described presently.

The pivoted distributor 36 is adapted to selectively discharge materialsfrom the stock pile conveyor 34 onto the receiving end of an inclinedconveyor 38 leading to the spray bin installation 30 or onto thereceiving end of a by-pass conveyor 40 which in turn discharges thematerial fed thereto onto the receiving end of the conveyor 28 so thatmaterials may be conducted directly from the stock pile 32 to the mixingplant 10 without being subjected to precooling treatment.

The conveyor 38 is employed for the purpose of conducting the coarseraggregates to the spray bin installation 30 for cooling purposes whilethe finer aggregates, such as sand, are directed to the conveyor 40 forbypassing directly to the mixing plant 10.

Referring now to Fig. l, the spray bin installation 30 has associatedtherewith means for supplying chilled water for spraying over the coarseaggregates conducted thereto by the conveyor 38 and toward this end arefrigeration plant 42 may be located adjacent the spray bininstallation and is adapted to receive a supply of coolant water from asurge tank 44 which in turn receives the heat-expended coolant waterfrom the spray bin installation 30. A water supply source 46 is providedfor replenishing any coolant water which may be lost in the process. Thespray bin installation 30, which will be described in detail presently,includes a shaker screen mechanism for screening the chilled aggregateto insure a more uniform moisture content of the aggregate before it isconveyed to the mixer installation, and the rejected moisture-ladenresidue from this shaker screen construction may be discharged to awaste pond 48.

Referring now to Figs. 1, 2 and 3, the precooling spray bin installation30 is similar in its general organization to the above mentionedOcto-Bin installation 10 and includes a frame-like structure 52 having atower section 54 provided with side walls 56 of which there arepreferably eight in number. The tower structure 54 also includes a roof58 and penthouse arrangement 60 in which there is disposed a pivoteddistributor hopper 62 designed for receiving the coarse aggregatesissuing from the discharge end of the conveyor 38 and for selectivelydistributing them into any one of a number of aggregate compartments 64(Figs. 1 and 3) of which there may be six in number.

The six aggregate compartments 64 are arranged radially in the towerstructure 54 and the usual cement tank such as is shown at 14 in themixer installation 10 has been omitted. The aggregates are selectivelydistributed to their respective compartments by means of the pivoteddistributor hopper 62. The sides of the aggregate compartments 64 slopesteeply and provide for free and fast flowing of the aggregates. Eachcompartment 64 is provided with a gate 66 which may be of clamshell typeand which may be electrically, pneumatically, hydraulically, orotherwise controlled. One pneumatic control for one of the gates 66 isdisclosed in Fig. 5 and will be described in detail subsequently.

The lower ends of the aggregate compartments 64 communicate with acollector cone 68 which is common to all of the gates 66 and the lowerend of the cone discharges onto a shaker screen assembly 70. Coarsematerials issuing from the screen are conducted directly onto theconveyor '28, the receiving end of which underlies the discharge end ofthe screen. An imperforate tray 72 which coextensively underlies thescreen discharges waste materials for conduction to the waste pond 48.

The gates 66 are not watertight and, during the time that coolant wateris being sprayed into the various compartments which are filled withcoarse aggregate, the heat expended coolant water may trickle or flowthrough the closed clamshell gates and be received upon a tiltabledeilector plate 67 (see also Fig. for selective directioninto a manifoldtrough or moat 69 encircling the installation from whence it may beconducted to the surge tank 44. Alternatively, the pivoted deflectorplate '67 may be so positioned as to direct the aggregate, when thegates 66 are open, into the collector -cone 68 after coolant water hasbeen drained from compartment 64.

The coolant water is conducted from the refrigeration plant 42 to avertical standpipe 80 which leads updirecting coolant fluid "downwardlyonto the aggregates contained within the respective compartments.

in practicing the method of the present invention, it is contemplatedthat one workman shall 'be stationed at a ground location adjacent thespray bin installation and that another workman shall be stationed inthe tower 54 thereof. The ground workman, the tower workman and suchworkmen as are employed 'at the central mixing plant 10 and at the stockpile 32, may be in constant communication with one another through asuitable telephonic communication system so that each may be appraisedof the requirements of the others in the performance of his respectiveduties. The ground workman may be provided with suitable controls foroperating the pivoted distributor 36 for the selective discharge ofmaterials from the conveyor 34 to the conveyors 38 and '40 and "he mayalso be provided with controls for operating the various gates '66 anddeflector plates 67 associated with "the respective aggregatecompartments 64.

A simplified control diagram for selective operation e of 'the pivoteddistributor '36 is shown in Fig. 4. In this diagram, the pivoteddistributor 36 is shown as being in the form or a gate member mounted ona vertical shaft 37 which carries a worm wheel 39 meshing with a worm 41mounted .on the motor shaft "4 3 of a reversible motor M. The gatemember or distributor 361s movable from the full line position whereinmaterials issuing from the conveyor 34 are directed to the 'conveyori38,to the dotted 'line position wherein the materials are directed to theconveyor 40. The motor 'M is connected through leads a and b to aconventional reversing switch S to which eurrentmay'be supplied from asuitable source, nots'hown. It is obvious that selective movements ofthe pivoted distributor 36 may be controlled from the ground station ofthe spray bin installation 30 by other means whether electric, hydraulicor otherwise.

Referring now to Fig. 5., a simplified control diagram for selectiveoperation of the various gates 66 and defiec'tor'pla'tes 67 at thebottom of the aggregate compartments 64 is shown. In this view theaggregate compartments are shown as being arranged linearly but it willbe "understood, of course, that actually they are arranged radiallyabout the central arr-is of the tower 56. Each or the aggregatecompartments '"64 is shown as being providcd an :air ram 90.Differential air pressure is available to control the operations of theair ram for'the various aggregate compartments. Toward. this end, thereis diagrammatically illustrated a source of pressure, as for example, :atank or reservoir 92 wherein the pressure is maintained at fifty pounds.Leading from this tank is a conduit or pipe 94 which connects with theinlet port 96 of a control valve V located at the ground station of thespray ib'in assembly 3 0.

Branches n, a, 'c', d, e and f lead from the valve to the various airrams 90. The valve V is provided with a core :98 having a directionalpassage 100 therein capable of selective communication with the inletport 96 and 'a series of outlet ports 1102 communicating with therespective branches a, b, c, etc. The gate 66 may normally remain closedunder the influence of gravity and upon operation of the individual airrams "90, the respective gates -66 are moved to their openpositionswhile at the same time the deflector plates '67 are moved so asto dedeer material visuing trorn the compartments 64 into the collectorcone 68.

iln practicing the invention for a particular installation, and forstarting up operations, the ground operator at the spray bin assembly30, being apprised of the requirements at the mixing plant 10, willordinarily call for the requisite quantity :and character of the coarseaggregate from the stock pile 32 which, when loaded at the receiving endof he conveyor 34, travels to the discharge end thereof where it isdirected by the pivoted distributor 36 onto'the conveyor 38. Thispivoted distributor, as previously de scribed, is operated under thecontrol of the ground op- :enator by manipulation of "the reverseswi'tdh 'S to a posi- :tion wherein the vertical shaft 37 is rotated ina counterclockwise direction, as viewed in Fig. 4, to bring the gate toone of its extreme limiting positions.

for purposes of illustration, will the assumed that three grades ofcoarse aggregate material are required in the final mixing and :are to:be cooled by the spray bin equipment at the installation 30. Thesematerials have been designated as fine, intermediate and coarse,respectively.

The material placed on the conveyor .38 is elevated to the towerstructure of the spray bin assembly lrrom whence it may be distributedto the various raggre'gate compartments 64 by proper manipulation :ofthe pivoted distributor hopper 62. Two adjacent compartments '64 may befilled with the coarse material, two other adjacent compartments may befilled with the intermediate material, and the remaining two adjacentcompartments may be filled with the line grade of material. After thecompar-tments :64 have been filled, all of the shut-0E valves 83 may beojpemd and coolant water allowed to new simultaneously onto theaggregate .in all of the compartments. The length of time during whichthis simultaneous spraying is maintained will vary :for 'difierent sizesof aggregates. However, many installations will accommodate cyclicoperation of the apparatus in such a mannor that a quantity of aggregateequal to the entire capacity of :all of the bins passes from the stockspile to the final mixing plant during the course of approximately onehour and ten minutes, allowing ten minutes for-the material in transit.This involves an hourly cycle of operation for the spraying bin assemblyand such cyclic operation :of the apparatus will accommodate a largevariety of conditions. For illustrative purposes, however, an instancehas been selected wherein the temperature of the aggregate arriving atthe tower of the spray bin assembly is between 70 and F. and wherein areduction in the temperature of the aggregate to approximately 43 F. isrequired when the cooled aggregatereaches themixer storage bins at themixing station 10. Obviously for certain other conditions the machinemay be run on afa'ster or slower cycle or the hourly cycle may bemaintained and the spraying and draining time for the aggregate maybevaried.

and F reading in a clockwise direction.

7 For descriptive purposes, in Figs. 1 and 3, the six aggregatecompartments have been labelled A, B, C, D, E

The compartments A and B may contain the coarser aggregates, thecompartments C and D may contain the intermediate aggregates, while thecompartments E and F may contain the smaller aggregates.

Under the conditions outlined above and assuming that the apparatus isto be operated upon the basis of an hourly cycle wherein materialissuing from the stock pile 32 will arrive at the mixing plant 10 in thecourse of one hour and ten minutes, it may be assumed that five minuteswill be required for passage of the material from the stock pile to thevarious aggregate compartments 64 and that another five minutes must beallowed for passage of the cooled material along the inclined conveyor28 to the mixing plant 10. This leaves a full hour for treatment of thematerial in the precooling apparatus 30. It has been found that in orderto effectively reduce the temperature of the coarser aggregates in thebins A and B to the desired low temperature, approximately fifty minutesof spraying time will be required. For the intermediate grade ofaggregate in the bins C and D, forty minutes may sutfice. For therelatively small aggregate in the bins E and F, one-half hour ofspraying time is sufiicient.

After the preliminary, simultaneous spraying of the aggregates in thevarious bins 64, and immediately prior to the commencement of regularmixing operations at the mixing plant 10, the spray bin apparatus may bestarted upon its regular hourly cycle basis. Thus after the coarseaggregates in the bins A and B have been sprayed by the coolant fluidfor approximately fifty minutes, the shut-off valve 83 of thecompartment A is completely closed and this compartment is allowed todrain for approximately ten minutes, after which time the groundoperator, by manipulation of the valve V, may open the clamshell gates66 associated with this compartment and allow the drained but stillmoist, cooled material in the compartment to issue to the collector cone68 beneath the gate. The material which passes through the collectorcone 68 is deposited upon the shaker screen 70 and the aggregate isthereby further relieved of a large portion of its remaining moisturecontent and also of any silt or other small sediment of attrition whichpasses through the screen, and this material is directed by theimperforate screen tray 72 to the waste pond 48.

The sprayer may then perform the necessary operations for draining thematerial in the compartment B which also contains relatively coarseaggregate. Thus, by closing the valve 83 associated with thiscompartment, the supply of coolant water issuing to this compartment iscompletely shut off and the aggregate is allowed to drain forapproximately ten minutes after which time the gates 66 are opened andthe material therein is emptied into the collector cone 68 forconduction to the shaker screen 70.

The purpose of the shaker screen 70 is to provide a more uniformmoisture content of the aggregate before it is conveyed to the mixerplant 10. The shaker screen is designed to throw off, to a large extent,the surface moisture remaining on the aggregate materials. The screenmesh of the shaker screen is sufficiently small as to serve for allsizes of material issuing from the aggregate compartments.

As soon as the cobble material has been discharged from the cobblecompartment A, this compartment is then ready to receive another chargeof the material. As regards the two compartments A and B, the alternatespraying operation lasting approximately fifty minutes and the drainingoperation lasting approximately ten minutes is carried out continuously.

Treatment of the intermediate material in the compartments C and D issimilar to that accorded the coarser material in the compartments A andB with the exception that the spraying and draining portions of theregular cycle are varied slightly. Inasmuch as it does not require quiteas long a period of spraying time to reduce the intermediate aggregateto the desired low temperature, this aggregate may be subjected to thespraying operation for approximately forty minutes. By the same token,the intermediate aggregate, since it is possessed of smallerinterstices, will require a longer period of draining time and thus theoperations performed upon the large aggregate in the compartments A andB may likewise be performed upon the aggregates in the compartments Cand D utilizing a forty minute period for spray and a twenty minuteperiod of drain to complete the regular apparatus cycle. The sprayingand draining of the materials in the compartments C and D may likewisebe conducted alternately just as in the case of the compartments A andB.

In a similar manner, the fine material in the compartments E and F maybe conducted'sirnultaneously with the treatment of the intermediatematerial and with the treatment of the coarse material. However, due tothe smaller interstices of the fine material in the compartments E andF, a shorter spraying time of thirty minutes and a longer draining timeof thirty minutes is resorted to thus completing a regular cycle for thesmall aggregate.

From the above description it will be seen that the coarse material inthe compartments A and B, the intermediate material in the compartmentsC and D, and the fine material in the compartments E and F are eachsubjected to alternate, but different, periods of spraying and drainingtime, respectively, and that the operations on these pairs ofcompartments are conducted simultaneously so that once during each hourcycle of the apparatus as a whole, a discharge of the partially drainedmaterial from each individual compartment to the collector cone takesplace. It is not necessary that any definite pattern of sequential.operation as regards the six compartments be placed in effect althoughfor smooth and continuous operation it is contemplated that the variousspraying and draining operations resorted to may take place according toa predetermined time chart. As the character of the aggregate reachingthe spray bin assembly varies slightly from time to time, the operatorwill in his best judgment vary the period of spraying time, of drainingtime, or both, to attain the-desired low temperature and moisturecontent of the materials leaving the precooling apparatus and depositedupon the conveyor 28 leading to the main mixing plant.

in the timing chart of Fig. 6, a purely arbitrary and more specific hourschedule has been illustrated for an installation calling forapproximately forty-five minutes spraying time for each of the coarsecobble aggregate compartments A and B, approximately ten minutesdraining time, four minutes filling time, and allowing one minutedischarge time; forty minutes spraying time for each of the intermediatecobble aggregate compartments C and D, fifteen minutes draining time,with the same filling and discharge time being allotted thereto; andapproximately thirty minutes spraying time and twenty-five minutesdraining time for the smaller cobble aggregate compartments E and F.

As previously described, the preliminary setting-up time consumesapproximately one hour. This includes simultaneous spraying of theaggregates in all of the compartments 64. When cyclic operation is ineffect, a short period of time, for example two minutes, is allowed fordischarging of the first compartment A and three minutes may be allowedfor the refilling thereof. At five minutes in the cycle the spraying ofthe coarse material in the compartment A may commence and about thistime the pivoted distributor 36 may be switched over to deliver sand tothe by-pass conveyor 40. The spraying operation continues until fiftyminutes in the cycle when draining of the compartment A is initiated byclosing the valve 83 which controls the spraying of the compartment A.At the end of the cycle the gate 66 of the compartment A is opened todischarge the contents thereof weaves.

9 and the discharge consumes approximately two minutes in the nextsucceeding cycle.

'While the compartment A is thus being treated, compartrnent B alsocontaining coarse cobble material receives its spraying operation fromfifteen minutes in the first cycle until the end of the cycle and thedraining operation is conducted during the first ten minutes of the nextcycle. Discharge of the compartment B takes place at ten minutes in thesucceeding cycle and recharging thereof takes place from twelve tofifteen minutes in this latter cycle. The operations for compartments Aand B are continuous throughout the various cycles.

The treatment of intermediate materials in the compartments C and D issubstantially the same as for the compartments A and B with theexception that the period of spraying time involved is forty minuteswith a fifteen minute period for draining as shown in the chart.Similarly, the treatment of the fine materials is shown in the chart asinvolving thirty minutes for the spraying operation and twenty-fiveminutes for draining time. In the case of each grade of material, thesame alternate or staggered spraying and draining periods are maintainedwith the treatment accorded the three grades of materials overlappingone another.

It is to be noted that the conveyor 34 leading from the stock pile 32 isin intermittent operation, supplying sand and cobble materials to theconveyors 40 and 38, respectively, in alternate fashion. As shown inFig. 2, the cooling plant and conveyor discharge to a common point orcollecting station on the conveyor 28 which thus carries at alternatetimes both the untreated sand and the cooled aggregates. That is, theconveyor 28 leading to the mixing plant 10 is in substantiallycontinuous operation supplying the discharged precooled materials or theuntreated sand alternately to the mixing plant 10. The deflector plates67 and the clamshell gates 66 operate under the same controls and theplates 67 direct expended coolant water to the surge tank 44 each timethe gates 66 corresponding thereto are closed during the spraying andthe draining periods of the respective compartments.

By practicing the invention as above presented, there is obtained asynchronized control of the movement of the batched materials suppliedfrom the stock pile 32 in conjunction with the batch charging device 62at the precooling plant and the batch charging device 17 at the mixingplant, and also in conjunction with the conveyor belts employed inconnection with the invention. By fol lowing the predetermined sequenceof operations, the possibility of over-charging the aggregatecompartments or any of the receivers associated with the invention isminimized. In this manner, the various aggregate charges are properlyseparated in transit to and from the precooling apparatus 30 as well asbeing properly separated while undergoing cooling treatment.

I claim as my invention:

1. A cyclically operable method of precooling a plurality of aggregatesof dilferent sizes prior to mixing the aggregates to form concrete, eachcycle of said method comprising the steps of assembling segregatedquantities of the aggregates, spraying the aggregates with cold waterfor diiferent fractions of the cycle in proportion to the sizes of theagregates, draining the respective aggregates for the remaining portionsof the cycle, said remaining portions thereby being inverselyproportional to the sizes of the aggregates, and removing saidquantities of the aggregates after draining, said spraying beinginitiated for the respective aggregates in staggered rotation throughoutsaid cycle so that said assembling and removing operations for therespective aggregates will also be staggered along said cycle.

2. In an apparatus for precooling concrete aggregates, a series ofclosely grouped aggregate compartments, a liquid permeable gate at thebottom of each compartment operable when closed to retain aggregate inthe compartmer t while permitting drainage of liquid therethrough,

closing said gates.

3. in an apparatus for precooling concrete aggregates, a series ofclosely grouped aggregate compartments, a liquid permeable gate at thebottom of each compartment operable when closed to retain aggregate inthe compartment whilepermitting drainage of liquid therethrough, acollector funnel common to all of said gates for receiving thedischarged aggregate from the various compartments when their respectivegates are opened, a shaker screen disposed beneath said collectorfunnel, a movable deflector plate disposed beneath each gate and movableto selectively direct material discharged from its respectivecompartment into said funnel or to divert the same from the latter,means operatively connecting said gates and deflector plates forpositioning the latter in their material-diverting positions when thegates are closed, means for selectively spraying coolant liquid over theaggregate in each compartment, means for opening and closing said gates,and means for actuating said shaker screen.

4. In an apparatus for precooling concrete aggregates, a series ofsector-shaped aggregate compartments arranged in closely groupedrelationship about a vertical .axis, there beinga drain anddischargeopening at the bottom of each compartment, a liquid-permeable gate foreach drain and discharge opening and operable when closed to retainaggregate Within the compartment while permitting liquid to escapetherefrom and operable when open to discharge the contents from saidcompartment, a collector funnel common to all of said gates forreceiving the discharged contents of said compartments, a shaker screendisposed beneath said collector funnel for receiving material dischargedtherefrom, means operable when said gates are closed for divertingliquid issuing from said compartments from said collector funnel andoperable when said gates are open to discharge the contents of thecompartments into said collector funnel, means for actuating said shakerscreen, means for operating said gates, and means for selectivelysupplying coolant liquid to said compartments for cooling the contentsthereof by direct heat transfer.

5. In an apparatus for withdrawing size-graded aggregates from astockpile, precooling the coarser aggregates, and delivering all of thewithdrawn aggregates to a mixing plant, said apparatus comprising acooling plant located intermediate said stock pile and mixing plant, adistributing station located intermediate the cooling plant and stockpile, a conveyor for conducting aggregates from said stock pile to saiddistributing station, a conveyor for coarse aggregates extending fromsaid distributing station to said cooling plant, a collecting stationadjacent said cooling plant, a conveyor for delivering materialsreceived at said collecting station to said mixing plant, a conveyorextending from said distributing station to said collecting station fortransporting fine aggregates from said distributing station to saidcollecting station, means at said cooling plant for cooling coarseaggregates delivered thereto, means at said cooling plant fordischarging the cooled coarse aggregates to said collecting station, andmeans for actuating all of said conveyors.

6. In an apparatus for withdrawing size-graded aggregates from a stockpile, precooling the coarse aggregates, and delivering all of theaggregates to a mixing plant, said apparatus comprising a precoolingplant located intermediate said stock pile and said mixing plant, adistributing station located intermediate said precooling plant and saidstock pile, a first conveyor extending from the stock pile to saiddistributing station, a second conveyor for coarse aggregates extendingfrom said distributing station to said precooling plant for deliveringcoarse aggregates thereto, a collecting station positioned adjacent saidprecooling plant, a third conveyor extending from said distributingstation to said collecting station for delivering fine aggregates to thelatter, a fourth conveyor leading from said collecting station to saidmixing plant, a distributor element adjacent the forward end of saidfirst conveyor movable from one extreme position wherein aggregateissuing from said first conveyor is directed onto said second conveyorto another extreme position wherein the aggregate is delivered to saidthird conveyor, means at said precooling plant for effecting cooling ofthe aggregate delivered thereto, means for discharging cooled aggregatesfrom said precooling plant directly onto said fourth conveyor, and meansfor selectively operating said distributor element.

7. In an apparatus for precooling a plurality of different concreteaggregates, the combination comprising an elevated bin having aplurality of compartments for holding quantities of the differentaggregates, means for filling said compartments in rotation with thedifferent aggregates, said compartments having respective gates fordischarging the aggregates from said compartments in rotation, means forselectively spraying cooling Water over the aggregates in saidrespective compartments for cooling the aggregates, the water drainingout of said compartments, means for collecting the aggregates from saidgates, and means for diverting the draining water from said lastmentioned means.

8. In an apparatus for precooling a plurality of concrete aggregates ofdifferent size grades, the combination comprising an elevated bin havinga plurality of compartments for holding quantities of the ditferentaggregates, a conveyor for raising the aggregates to the top of the bin,means for selectively loading said conveyor with any of the differentaggregates, means for selectively directing the aggregates from saidconveyor into any of said compartments to fill said compartments inrotation with the different aggregates, respective gates at the bottomsof said compartments for discharging the different aggregates therefromin rotation, means for selectively spraying cooling water into saidcompartments for cooling the aggregates in rotation, said gates beingliquid permeable so that the water will drain therethrough from saidcompartments, a collector funnel underlying all of said gates forreceiving the cooled aggregates therefrom, said compartments havingrespective diverting means operative when said gates are closed todivert the water fromsaid funnel, a shaker screen for receiving theaggregates discharged by said funnel and removing excess water from theaggregates, means for receiving and carrying 01f the cooled aggregatesfrom said shaker screen, and means for carrying off the water from saiddiverting means.

References Cited in the file of this patent UNITED STATES PATENTS713,671 Oliver Nov. 18, 1902 1,304,619 Stamp May 27, 1919 1,704,268Venable Mar. 5, 1929 1,828,458 Butler Oct. 20, 1931 1,871,166 FahrbachAug. 9, 1932 2,138,277 Johnson Nov. 29, 1938 2,183,896 Rupp et al. Dec.19, 1939 2,276,471 Eberhart Mar. 17, 1942 2,397,959 Gephart Apr. 9, 19462,480,727 Greyson Aug. 30, 1949

1. A CYCLICALLY OPERABLE METHOD OF PRECOOLING A PLURALITY OF AGGREGATESOF DIFFERENT SIZES PRIOR TO MIXING THE AGGREGATES TO FORM CONCRETE, EACHCYCLE OF SAID METHOD COMPRISING THE STEPS OF ASSEMBLING SEGREGATEDQUANTITIES OF THE AGGREGATES, SPRAYING THE AGGREGATES WITH COLD WATERFOR DIFFERENT FRACTIONS OF THE CYCLE IN PROPORTION TO THE SIZES OF THEAGREGATES, DRAINING THE RESPECTIVE AGGREGATES FOR THE REMAINING PORTIONSOF THE CYCLE, SAID REMAINING PORTIONS THEREBY BEING INVERSELYPROPORTIONAL TO THE SIZES OF THE AGGREGATES, AND REMOVING SAIDQUANTITITES OF THE AGGREGATES AFTER DRAINING, SAID SPRAYING BEINGINITIATED FOR THE RESPECTIVE AGGREGATES IN STAGGERED ROTATION THROUGHOUTSAID CYCLE SO THAT SAID ASSEMBLING AND REMOVING OPERATIONS FOR THERESPECTIVE AGGREGATES WILL ALSO BE STAGGERED ALONG SAID CYCLE.